I haven't seen highbush cranberries growing right in swamps, but I've seen them in places that flood with snow melt in the spring.
What height range are you looking for?
Here's a PDF you might find useful: http://centralwashingtonfirerecovery.info/2012/wp-content/uploads/NRCS/WetlandPlantings.pdf
The King County (down in Washington) website has a plant finder, too, and comes up with some good results when searching for "shrub" and "wet": https://green2.kingcounty.gov/gonative/Plant.aspx?Act=search. Here's some of the one's on the list. I bolded the ones I know to be edible. I wonder about the Nootka Rose and blackcap raspberry liking standing water, as they grow naturally on my property in drier places:
bald hip rose, black cap raspberry, black gooseberry, bog laurel, bog rosemary, devil's club (the name really fits it...), highbush cranberry, nootka rose, Pacific ninebark, red-osier dogwood (supposedly edible roots, shoots, stems and seeds), salmonberry, douglas' spiraea/hardhack, stink currant (tastes like pine), subalpine spirea, swamp rose, sweet gale, tall Oregon grape, twinberry